The stability of a straight or a circular sawblade is affected by the cutting forces of the sawteeth. It is depending upon the form, tension and material of the blade. The main reason for deviations from an ideal cut are the sideforces acting against the sawteeth. Those forces originate from assymetric or deformed teeth and from the variable texture and hardness of the workpiece (saw timber). Due to variations in the workpiece there always will occur, even with an ideal toothform, sideforces followed by bending of the blade.
Also the cutting force components in the sawplane perpendicular to the tooth-movement, often called feeding-force and generally directed towards the tooth, imparts a buckling effect and an additional side force. If the body of the blade is not stiff enough this causes a critical deflection.
When sawing material with pronounced texture like wood, blades with great stiffness are used. This is brought about by using strong pretensioning and material with considerable thickness and stiffness. The sawblades of today with these fixed attributes can be considered as passive tools. A forced disturbance cannot be eliminated, it can only be counteracted by reaction forces due to the side displacement of the tooth front.
It is an object of the present invention to provide a saw unit which can be effectively steered.